This invention relates to apparatus and method of forming a matte finish on resin-coated webs or sheets, such as developer sheets used in conjunction with photosensitive imaging systems employing microcapsules to provide visible images upon contact with a color precursor. Such photosensitive imaging systems employing microencapsulated radiation sensitive compositions are the subject of commonly assigned U.S. Pat. Nos. 4,399,209, 4,416,966, and 4,440,846.
The imaging systems described in the aboveidentified patents are characterized by an imaging sheet including a layer of microcapsules which contain photosensitive composition in the internal phase which is image-wise exposed to actinic radiation. U.S. Pat. No. 4,399,209 discloses a transfer system in which the imaging sheet is assembled with a developer sheet prior to being subjected to a rupturing force. Upon passing through a pressure developer, the microcapsules rupture and image-wise release the internal phase whereupon the color precursor migrates to the developer sheet where it reacts with the dry developer and forms a color image.
Developer sheets or webs of such sheet material are provided with a resin on the surface which may be glossed by the application of heat and pressure, while supporting the sheet or web with the resin against a smooth or highly polished surface. The surface may be that of a heated convex plate, a roll, or a belt.
A belt-type glosser for applying a gloss finish to such developer sheets is described and claimed in the copending application of Stone et al, Ser. No. 017,102 filed Feb. 19, 1987, now Patent No. 4,761,311, and assigned to the same assignee as this invention, the disclosure of which is incorporated herein by reference. In the above-identified application, the polymer belt forms the glossing surface for the softening and finishing of the resin coating by the transfer of heat and pressure from a heated surface in running contact with the opposite side of the belt.
Typical thermoplastic developer resins which are capable of forming a film upon the application of heat and pressure are rather tacky compared to dry silver film, conventional film and xerographic copies. Thus, the release conditions of the developer sheet surface from the belt can be critical.
It is desirable to be able to provide a matte or textured finish to such developer web or sheet material, as may be preferred or desired. However, a conventional matte finish, formed in a belt or on a roll as a mirror image of a fine fabric woven or the like does not provide a satisfactory casting surface for the resin, in view of the strong tendency of the resin to adhere to such surface following the application of heat and pressure. This is due to the formation of mechanical locks between the resin and the surface.